From: Dennis Zhou <dennis@kernel.org>
To: David Sterba <dsterba@suse.cz>
Cc: Dennis Zhou <dennis@kernel.org>, David Sterba <dsterba@suse.com>,
Josef Bacik <josef@toxicpanda.com>, Chris Mason <clm@fb.com>,
Omar Sandoval <osandov@osandov.com>,
Nick Terrell <terrelln@fb.com>,
Nikolay Borisov <nborisov@suse.com>,
kernel-team@fb.com, linux-btrfs@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 09/12] btrfs: change set_level() to bound the level passed in
Date: Tue, 5 Feb 2019 14:59:55 -0500 [thread overview]
Message-ID: <20190205195955.GA28437@dennisz-mbp.dhcp.thefacebook.com> (raw)
In-Reply-To: <20190205195414.GA2900@twin.jikos.cz>
On Tue, Feb 05, 2019 at 08:54:15PM +0100, David Sterba wrote:
> On Tue, Feb 05, 2019 at 02:32:54PM -0500, Dennis Zhou wrote:
> > On Tue, Feb 05, 2019 at 08:06:37PM +0100, David Sterba wrote:
> > > On Mon, Feb 04, 2019 at 03:20:05PM -0500, Dennis Zhou wrote:
> > > > -unsigned int btrfs_compress_str2level(const char *str)
> > > > +unsigned int btrfs_compress_str2level(unsigned int type, const char *str)
> > > > {
> > > > - if (strncmp(str, "zlib", 4) != 0)
> > > > + unsigned int level;
> > > > + int ret;
> > > > +
> > > > + if (!type)
> > > > return 0;
> > > >
> > > > - /* Accepted form: zlib:1 up to zlib:9 and nothing left after the number */
> > > > - if (str[4] == ':' && '1' <= str[5] && str[5] <= '9' && str[6] == 0)
> > > > - return str[5] - '0';
> > > > + if (str[0] == ':') {
> > > > + ret = kstrtouint(str + 1, 10, &level);
> > >
> > > The docs kstrtouint of say that initial + is also accepted, I'd rather
> > > keep the level specification strict, ie. no "zlib:+3" and no garbage
> > > after the number.
> > >
> > > The validation is currently missing but I think we should catch levels
> > > out of range during mount/remount. The fallback to default is a safety
> > > but wrong specification should be communicated to the user early.
> >
> > Ok. To make sure I understand properly for improper level (ie "30",
> > "+3", "+3d") set the level to default (already done) and pr_warn saying
> > invalid level?
>
> So we have (at least) two ways how to handle:
>
> - warn and fail the mount -- catch typos and the like, continuing with
> default could cause problems later though not that severe as the
> compressionw would be different than expected, but this could be
> considered a usability bug
>
> - only warn and continue with the default -- not mounting a root
> filesystem just because of a typo can be worse than mounting with
> wrong level; as long as there's a warning in the log, the user still
> has a working system and can fix it manually
>
> Both have some pros and cons and initially I was more inclined to pick
> the 1st option, but now that I'm thinking about that again, the other
> has some merit.
>
> Given that zlib now falls back to default for unrecognized level, we
> should probably stick to that for zstd too.
Ok. With that I'll run a v3 adding a warning for a '+' or invalid input.
I think moving compression to being a property rather than a mount
option would be ideal. That would enable multiple compression levels per
mount and prevent remounting with incorrect mount options.
Thanks,
Dennis
next prev parent reply other threads:[~2019-02-05 20:00 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-04 20:19 [PATCH v2 00/12] btrfs: add zstd compression level support Dennis Zhou
2019-02-04 20:19 ` [PATCH 01/12] btrfs: add helpers for compression type and level Dennis Zhou
2019-02-04 20:19 ` [PATCH 02/12] btrfs: rename workspaces_list to workspace_manager Dennis Zhou
2019-02-04 20:19 ` [PATCH 03/12] btrfs: manage heuristic workspace as index 0 Dennis Zhou
2019-02-04 20:20 ` [PATCH 04/12] btrfs: unify compression ops with workspace_manager Dennis Zhou
2019-02-04 20:20 ` [PATCH 05/12] btrfs: add helper methods for workspace manager init and cleanup Dennis Zhou
2019-02-04 20:20 ` [PATCH 06/12] btrfs: add compression interface in (get/put)_workspace() Dennis Zhou
2019-02-04 20:20 ` [PATCH 07/12] btrfs: move to fn pointers for get/put workspaces Dennis Zhou
2019-02-04 20:20 ` [PATCH 08/12] btrfs: plumb level through the compression interface Dennis Zhou
2019-02-04 20:20 ` [PATCH 09/12] btrfs: change set_level() to bound the level passed in Dennis Zhou
2019-02-05 19:06 ` David Sterba
2019-02-05 19:32 ` Dennis Zhou
2019-02-05 19:54 ` David Sterba
2019-02-05 19:59 ` Dennis Zhou [this message]
2019-02-06 16:48 ` [PATCH v2 " Dennis Zhou
2019-02-04 20:20 ` [PATCH 10/12] btrfs: zstd use the passed through level instead of default Dennis Zhou
2019-02-04 20:20 ` [PATCH 11/12] btrfs: make zstd memory requirements monotonic Dennis Zhou
2019-02-04 20:20 ` [PATCH 12/12] btrfs: add zstd compression level support Dennis Zhou
2019-02-05 19:26 ` [PATCH v2 " Dennis Zhou
2019-02-06 16:47 ` [PATCH v3 " Dennis Zhou
2019-02-05 14:57 ` [PATCH v2 00/12] " David Sterba
2019-02-05 16:03 ` Dennis Zhou
2019-02-05 16:27 ` David Sterba
2019-02-05 16:30 ` Dennis Zhou
2019-02-05 16:51 ` David Sterba
2019-02-05 17:07 ` David Sterba
2019-02-05 18:27 ` David Sterba
2019-02-05 18:30 ` Dennis Zhou
2019-02-05 20:48 ` Dennis Zhou
2019-02-06 15:15 ` David Sterba
2019-02-06 16:51 ` Dennis Zhou
2019-02-07 16:59 ` David Sterba
2019-02-07 17:36 ` Dennis Zhou
2019-02-08 13:22 ` David Sterba
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